Metal working



' W. C. M BAIN METAL WORKING Filed Sept. 29, 1928 Patented Sept. 25, 1934 UNITED STATES PATENT OFFICE METAL WORKING Application September 29, 1928, Serial No. 309,301

12 Claims.

The present invention relates to' a method of metal working. The invention has to do more particularly with the elongation of metal pieces in the form of strip sheets, flat wire, bars, and the like, to bring about their elongation by the use of unusual tension in the piece.

According to my invention, rolls are used as dies having rolling frictional engagement with the piece of metal being worked. A high tensional force, ordinarily a large fraction of the elastic limit of the metal, is employed to draw out the metal. By this method it is necessary to position the metal working rolls at a given setting, and then with a high pull applied to the protruding end of the piece, draw it through the rolls. Thus all the compressive force exerted upon the piece by the rolls combines with the high tensional force to produce a resultant force which exceeds either component force in intensity and is sufficient to cause a flow of the metal. Several such passes result in a rapid elongation of the piece without repeated annealings. It is also possible with accurately faced rolls to produce a very thin product. The product in the form of steel strip produced in this way will have no appreciable spread.

The method which I have devised applies chiefly to cold rolling. In ordinary cold rolling of strip metal, it has been found that considerable heat is generated in the material being rolled and that a considerable portion of the heat is transferred to the work rolls themselves. The undue heating of the rolls distorts them and the result is often poor rolling.

The main advantages resulting from the use of my method over that of a lesser tension are (1) lessened roll pressures in the mill and (2) apparently a greater toughness in the rolled prodnot, (3) reduction of internal lateral strains, resulting in flatter strip and reduction of .fractured edges to a negligible quantity, and the possibility of controlling the roll bending by means of tension regulation and thereby offsetting to an appreciable extent the effects of varying roll temperatures as the mill comes up to heat, (5) the possibility of controlling the roll bending by regulating the amount of tension to vary the roll pressure adjacent the middle of the rolls as compared to that adjacent the ends of the rolls, thereby controlling or assisting to control the contour of the rolled strip, (6) the guiding of the strip into the mill solely or partially by the tension on the entering portion; and (8) the flattening of the strip which results from rolling it under tension. The main advantages resulting from the use of my method over that of a higher tension are (1) the saving in expense by means of the use of a lighter pulling mechanism, (2) the maintenance of a larger margin of safety below the rupturing point in the strip than where elastic limit tensions are used, thus reducing the breakage, (3) greater ease of adjusting the tensions to compensate for the varying coil diameters on account of the greater permissible variation in tension in the strip without causing rupture.

By using a large fractional value of the elastic limit as a pulling force, while keeping the compressive forcesuch that the resultant force will produce a flow of metal in the strip, many passes and many reductions may be had between an- .nealings and in most grades of steel practically no cracking occurs at the edges. When the spread of the strip in rolling is zero, it is evident that the stresses in the strip are more uniform throughout the entire width of the strip than where there is a lateral flow of the metal in addition to its flow in a longitudinal direction. This is due to the fact that the lateral flow being cumulative is more pronounced at the edges than at the center.

One of the objectionable effects of the strained edges is found when a wide strip is subsequently slit into narrow widths. Where strains are left in the original wide strip, slitting relieves these strains but, unfortunately, by putting curves into the narrow strip. When the original strip is with out strains and is flat, it is evident that with the same care in slitting, it may be slit into straighter narrow strips, than where the original strip contains strains near the edges such as those due to lateral spread. The relation of tension to compression that I aim to cover herein is that in which the internal strains are reduced to a mini mum by reducing the spread approximately to zero through a proper relationship of tension and compression. Another advantage of the elimination of strains near the edges of the strip due to side spreading is in the reduction of fractures in the edges to a negligible quantity. Another evidence of the lack of strains in the finished strip when rolledby my method is in the degree of flatness that can be obtained in the finished strip. With the same rolls, it is possible to obtain flatter strip with the higher tensions than with low tensions or with no tension.

The apparatus for carrying out my new method may take dilferent forms, but preferably I employ reels to handle the piece being worked upon. One reel serves during the travel of the piece in one direction to wind up the piece while the other winding, now unwinds.

reel, unwinding, pays it off; when the direction of travel of the piece is reversed the reel functions are reversed, and the reel which has been unwinding, now winds, and the reel which had been The reels as shown are mounted on tilting frames, as1shown, when it is desired to use the travel of the tilting frame for entering the strip into the rolls in a horizontal plane, an indication of the amount of tension in the strip, or as a means for automatically controlling the speed of the motor mounted thereon, and thereby regulating the tension in the strip. The latter are suitably counter-weighted and carry motors for driving the reels. Preferably these motors are electric motors. The control for driving in alternate directions may be had by clutches or by electric switches, or both.

Having pointed out. the general character and nature of the invention, we may now pass to a consideration of the preferred embodiment of the same, set forth in the following description and illustrated in the accompanying drawing. For the scope of the invention, attention is directed to the appended claims.

In said drawing, Fig. 1 is a diagrammatic view illustrating apparatus constructed in accordance with the present invention and intended to carry out the method of the present invention, parts being shown in section taken on a plane indicated by the line 11 of Fig. 2; Fig. 2 is a plan view of the same apparatus; and Fig. 3 is a diagram of modified electrical circuits. Throughout these views like characters refer to like parts.

Referring to the drawing in d tail, A designates the stand of rolls by which the metal piece is to be reduced, 13, 13' the reels for winding and unwinding the picce, C, C the electric motors for driving the reels, D, D the tilting frames upon which the reels and motors are mounted, and W, W the counter-weights for holding the tilting frames in proper position.

The stand A includes two rolls 10 and 11 which operate as reducing rolls upon the piece of work P which passes between them. These rolls are preferably truly cylindrical throughout their work-engaging surfaces and have such surfaces well finished. The pressure of the rolls upon the piece is controlled by suitable screw-down mech-- anism, and the directions of application of the forces applied thereby are indicated by the arrows above and below the rolls. Power may or may not be applied to drive the rolls 10 and 11. Any approved screw-down mechanism and driving connections may be employed. Many are available in the art and the designer can make his own choice. When not driven, the freely rotatable rolls furnish restraint to the piece of work passing between them with a sort of die action, the roll surfaces serving as die surfaces having rolling frictional engagement with the surfaces of the piece of metal being elongated.

As clearly shown, the metal piece P is wound at its ends upon the reels B and B. At intermediate points between the reels it passes between the die rolls l0 and 11. The reels are intended to be operated alternately to pull the work in opposite directions. By properly setting the rolls for each change in direction, the to and fro movements of the piece will bring about corresponding reductions in the thickness of the piece.

I The tilting frames D and D' and the parts carried by them are the same in construction, but reversely arranged. The reel B has its axle 12 mounted in bearings in the end of the frame D axle 12' similarly mounted in the adjacent end of the frame D. The motors C and C are mounted, respectively, on shelves 13 and 13. The shelf 13 extends between the triangular frame members 14 and 15 of frame D. In like manner, the shelf 13 extends between the similar members 14 and 15 of frame D.

In the case of motor C, power is transmitted to the reel B through a train of gearing including pinion 16, gear wheel 17, pinion 18, and gear wheel 19. Pinion 16 is mounted upon a stud shaft 9 in line with the shaft of motor C. The pinion and motor shaft may be clutched together by a clutch 20, manually operated by a lever 21, pivoted upon a cross-bar 22, extending between the frame members 14 and 15. The gear-wheel 19 is mounted upon the axle 12 of the drum B. The gear-wheel 17 and the associate pinion 18 are mounted upon an in ermediate stud shaft 23, projecting from the frame member 15. The corresponding parts associated with reel B and motor C, are designated by the same numerals primed.

The frames D and B may be supported in any desired way. In the present'instance, the frame D is provided with a transverse rod 24 which extends through openings in the members 14 and 15 and openings in the lower ends of hangers 25 and 26. In the case of the frame D', the corresponding parts are rod 24' and hangers 25' and 26'. In both cases the reel motor and gearing are mounted upon one side of the pivotal supporting rod and consequently the tendency to move downward under the force of gravity must be neutralized by some force applied on the opposite side of the pivotal supporting rod. In the embodiment shown, the frame D is provided with a weight W and the frame D with a weight W for this purpose. The weight W is mounted upon a rod 2'7 which terminates at its upper'end in a hook 28 which rests upon a transverse rod 29 extending between the members 14 and 15 of the frame. The corresponding parts associated with the weight W and the frame D are the rod 2'7, the hook 28',and the transverse rod 29'.

It will be seen that the various rods and transverse members connecting the frame members 14 and 15, in the case of the frame D, and the frame members 14' and 15', in the case of the frame D, serve to give rigidity to the frame structure in each case and thereby strengthen it for the work it has to do.

The motor and reel may or may not be mounted upon a tilting frame. In what we have described heretofore, the motor and reel are in each instance mounted upon a tilting frame. Obviously, the frames D and D might be held from tilting in many ways. These need not be gone into but it is merely desired at this time to inelude in the disclosure frames D and D which do not tilt.

In one form of my invention in connection with these tilting frames D and D and their action during the winding and unwinding of the strip P, it may be noted that as the diameters of the coils of wound-up material on the reels B and B increase and decrease, the frames D and D tilt so as to maintain the strip in horizontal alignment with the pass between the reducing rolls 10 and 11.

In the diagram the downward pull on the tilt ing frame is represented diagrammatically by the weight W. I do not desire to have this mechanism limited to the counterweight as shown. In fact,

any mechanism that will exert a suitable predetermined pull in place of the weight may be substituted for said weight. In another form of my invention the tilting of the frame will furnish an indication of the amount of tension in the strip. In still another form of my invention the amount of pull W or W to maintain the tilting frame in normal position will indicate the tension in the strip. Likewise the tilting of the frame D and D may be used to automatically control the tension in the strip. In the latter case, movement of the tilting frame may be used to actuate a holding back or work retarding mechanism on the work entering side of the mill.

The moto rs C and C, which drive the reels B and B respectively, are preferably electric motors supplied with current from supply wires 30 and 31 leading from a suitable source of supply of electricity. In Figure 1, the motor C and C are thrown into series with each other and the source of electric energy through the conductors 30 and 31 by closing the two switches 32 and 32', after which the circuit may be interrupted by opening one or both of the switches 32 and 32. A suitable source of electricity and suitable control systems for the two motors C and C are described and claimed in my application Serial No. 628,846.

Instead of having the motors connected in series, it may be desirable in some instances to connect them in parallel. Such a parallel connection is shown in Fig. 3. Thus, in the case of motor 0, current would flow from conductor 30 through the left-hand blade of switch 32 and conductor 34 to the windings of the motor and back through conductor 35 ,and the right-hand blade of switch 32 to conductor 31. Similarly, in the case of motor C, current would flow from conductor 30 through the left-hand blade of switch 32' and conductor 34' to the windings of the motor and back through conductor 35' and the right-hand blade of switch 32', to conductor 31.

The motors C and C may be so connected as to have directions of motions which when transmitted to the reels B and B will produce tension in the strip or other piece of work P. In other words, the motors C and C pull on the work P in opposite directions. The use of a generator on the unwinding reel to produce back tension in the strip is covered in my Patent No. 1,881,056.

In carrying out my invention, it will be clear that the rolls l0 and 11 may be set with any desired pressure upon the strip P. In one form of my invention the reel 3 may be disconnected from its driving motor by means of clutch 20 and reel 13' connected to its motor C through its clutch 20. The reel B would then wind up the piece P and, as it did so, exert tension upon it. The control of the motor C as a pulling motor may be varied in any suitable way so as to apply the requisite tension to the piece P as it passes through between the rolls lO'and 11. The tension thus exerted is preferably from one-third to four-fifths the elastic limit of the piece. When the strip has been run toward the right, as viewed in Fig. 1, until it has been almost all unwound from the reel B, then the direction of travel of the strip is reversed. If further reduction is to be made, the rolls 10 and 11 are again set and motor C now becomes the pulling motor and reel B becomes the winding-up reel. The reel B then acts as the unwinding reel and is retarded by its motor acting as a generator, or an equivalent restraining mechanism. The motor C now must be controlled in like manner to the motor C, as previously described, in order to regulate the pull upon the piece P to bring that pull within the desired limits. Preferably, as before, the tension should be from one-third to four-fifths the elastic limit of the piece.

From what has been said, it will be seen that the rolls 10 and ll, when undriven, have a reducing' action similar to that of dies and confine the piece of work to the limits to which they are set. As such metal rolling rolls they furnish rolling frictional engagement with the piece of work as it passes through. It will also be clear that the rolls instead of being idly rotated by the pull of the work itself, might be rotated by power means applied directly, or by the combination of power means applied to the rolls with a portion of the rotative effort being transmitted to the rolls through the pull of the strip without materially altering their action. In fact, a considerable portion of the power could be exerted by driving the rolls in my tension method of rolling metal and still differ from the present art of rolling. It should be understood that many rollings of the piece of metal being worked upon take place without any intermediate annealing of the piece. Ordinarily, the piece is annealed to start with, but not annealed again until several reductions are fully completed in the apparatus shown. Then the finally reduced strip or other piece of work may be re-annealed, if desired; and in some cases is subjected to a further very ligh pass known as a skin pass.

With respect to the apparatus it will be apparent that some changes and alterations may be made in it without avoiding the invention in its broad scope. It is, therefore, intended to cover all alterations and modifications which rightly come within the scope of the invention by the arms of the appended claims.

What I claim as new and desire to secure by means of patent of the United States is:

1. A method of making strip which includes the steps of drawing the strip through reducing rolls under a tension from one-third to threefourths of the elastic limit, and adjusting the rolls to exert a similar pressure upon the material whereby the resultant of said pressure and tension exceeds the elastic limit and causes a flow of the core of the strip without spreading.

2. A method of rolling strip which includes the steps of drawing the strip through reducing rolls under tension from one-third to three-fourths of the elastic limit and adjusting the rolls to exert a pressure upon the material of from one-third to three-fourths of the elastic limit.

3. A method of rolling strip which includes the steps of drawing the strip through reducing rolls under tension from one-third to three-fourths of the elastic limit and adjusting the rolls to exert a pressure upon the material-of from onethird to three-fourths of the elastic limit, so that the resultant of said pressure and said tension exceeds the elastic limit and produces a longitudinal flow of the metal in the strip without side spreading.

4. A method of rolling strip which includes the steps of pulling the strip from between reducing rolls with tension from one-third to three-fourths of the elastic limit and of restraining the strip as it enters the rolls so as to reduce the roll pressure required to cause the metal in the strip to flow, said roll pressure being less than three-fourths but greater than one-third of what the roll pressure would be to produce the same reductions if the rolls were driven and no tensions applied to the strip.

5. In a method of reducing strip between rolls,

strip in the absence of substantial forward and back tensions thereon.

6. A method of rolling strip which includes the steps of pulling the strip between reducing rolls under a tension from one-third to three-fourths of the elastic limit, and restraining the strip as it enters the rolls so as to at least partially guide said strip between the rolls, and to reduce the roll pressure required to cause the metal in the strip to flow, said roll pressure being less than threefourths but greater than one-third of what the roll pressure would be to produce the same reductions if the rolls were driven and no tensions applied to the strip.

. 7. A method of rolling strip which includes the steps of pulling the strip from between reducing rolls with tension from one-third to three-fourths of the elastic limit and of restraining the strip as it enters the rolls so as to reduce the rollpressure required to cause the metal in the strip to flow, said roll pressure being less than threefourths but greater than one-third of what the roll pressure would be to produce the same reductions if the rolls were driven and no tensions applied to the strip, said tension and said restraining being suflicient at least partially to flatten the strip leaving the rolls.

8. A method of rolling strip which includes the steps of pulling the strip between reducing rolls under tension from one-third to three-fourths of the elastic limit and restraining the strip as it enters the rolls to guide said strip, at least partially, between the rolls. 4

9. A method of rolling strip which include. the steps of pulling the strip between reducing rolls under tension from one-third to three-fourths of the elastic limit, and restraining the strip entering the rolls, said tension and said restraining being sufllcient, at least partially, to flatten the strip leaving. the rolls,

10. In a method of rolling strip, the steps including passing it between reducing rolls and straightening the material during rolling by subjectin'g it to a tension between one-third and three-fourths of the elastic limit of the material being rolled.

11. In a method of rolling strip in a rolling mill, the steps including guiding the strip into the rolls of the mill by subjecting it to a back tension of from one-third to three-fourths of the elastic limit of the material being rolled.

12. In a method of rolling strip in a rolling mill, the steps including guiding the strip into the rolls of the mill, assisting the guiding of the material by subjecting it toa back tension, and winding the strip issuing from the mill while subjecting it to a tension between one-third and three-fourths of the elastic limit of the material being rolled.

WILLIAM C. McBAIN.

CERTIFICATE OF CORRECTION.

Patent No. 1,974,685.

September 25, 1934.

WILLIAM G. McBAIN.

It is hereby certified that error appears in the printed specification of the 'above numbered patent requiring correction as follows:

Page 3, line 83, or

"rolling" read working; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Off ice.

Signed and sealed this 16th day of October, A. D. 1934.

(Seal) Leslie Frazer Acting Commissioner of Patents.

strip in the absence of substantial forward and back tensions thereon.

6. A method of rolling strip which includes the steps of pulling the strip between reducing rolls under a tension from one-third to three-fourths of the elastic limit, and restraining the strip as it enters the rolls so as to at least partially guide said strip between the rolls, and to reduce the roll pressure required to cause the metal in the strip to flow, said roll pressure being less than threefourths but greater than one-third of what the roll pressure would be to produce the same reductions if the rolls were driven and no tensions applied to the strip.

. 7. A method of rolling strip which includes the steps of pulling the strip from between reducing rolls with tension from one-third to three-fourths of the elastic limit and of restraining the strip as it enters the rolls so as to reduce the rollpressure required to cause the metal in the strip to flow, said roll pressure being less than threefourths but greater than one-third of what the roll pressure would be to produce the same reductions if the rolls were driven and no tensions applied to the strip, said tension and said restraining being suflicient at least partially to flatten the strip leaving the rolls.

8. A method of rolling strip which includes the steps of pulling the strip between reducing rolls under tension from one-third to three-fourths of the elastic limit and restraining the strip as it enters the rolls to guide said strip, at least partially, between the rolls. 4

9. A method of rolling strip which include. the steps of pulling the strip between reducing rolls under tension from one-third to three-fourths of the elastic limit, and restraining the strip entering the rolls, said tension and said restraining being sufllcient, at least partially, to flatten the strip leaving. the rolls,

10. In a method of rolling strip, the steps including passing it between reducing rolls and straightening the material during rolling by subjectin'g it to a tension between one-third and three-fourths of the elastic limit of the material being rolled.

11. In a method of rolling strip in a rolling mill, the steps including guiding the strip into the rolls of the mill by subjecting it to a back tension of from one-third to three-fourths of the elastic limit of the material being rolled.

12. In a method of rolling strip in a rolling mill, the steps including guiding the strip into being rolled.

WILLIAM C. McBAIN.

CERTIFICATE OF CORRECTION.

Patent No. 1,974,685.

September 25, 1934.

WILLIAM G. McBAIN.

It is hereby certified that error appears in the printed specification of the 'above numbered patent requiring correction as follows:

Page 3, line 83, or

"rolling" read working; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Off ice.

Signed and sealed this 16th day of October, A. D. 1934.

(Seal) Leslie Frazer Acting Commissioner of Patents. 

